Faculty of Geosciences and Civil Engineering, Kanazawa University, Kanazawa, Japan E-mail:
Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan.
J Water Health. 2020 Dec;18(6):879-889. doi: 10.2166/wh.2020.013.
This study investigated the impact of each treatment stage of the activated sludge process on the fate of antibiotic resistant bacteria (ARB) in wastewater treatment plants (WWTPs). Wastewater and sludge samples were collected monthly at each stage of a commercial-scale WWTP. After 20-25 strains of indicator Escherichia coli were isolated from each sample on Chromocult Coliform Agar, antibiotic resistance of the isolates to amoxicillin (AMX), ciprofloxacin (CIP), norfloxacin (NFX), kanamycin (KM), sulfamethoxazole/trimethoprim (ST) and tetracycline (TC) were tested with the Kirby-Bauer disk diffusion method. As a result, activated sludge in the aeration tank and return sludge had higher abundance of antibiotic resistant E. coli than influent wastewater and secondary treatment effluent. AMX resistant E. coli was enriched in return sludge at the secondary clarifier. Higher temperature was also likely to cause an increase of AMX resistant E. coli in sludge. The antibiotic resistance profile of E. coli in secondary treatment effluent was more dependent on activated sludge than influent wastewater. These results suggested that activated sludge in WWTP possibly serves as a reservoir of ARB, and that behavior of ARB in WWTP differs by antibiotic classes.
本研究调查了活性污泥工艺的各个处理阶段对污水处理厂（WWTP）中抗生素耐药细菌（ARB）命运的影响。每月在商业规模 WWTP 的每个阶段收集废水和污泥样品。从每个样品的 Chromocult 大肠菌琼脂上分离出 20-25 株指示性大肠杆菌后，采用 Kirby-Bauer 圆盘扩散法测试分离株对阿莫西林（AMX）、环丙沙星（CIP）、诺氟沙星（NFX）、卡那霉素（KM）、磺胺甲噁唑/甲氧苄啶（ST）和四环素（TC）的耐药性。结果表明，曝气池中的活性污泥和回流污泥中抗生素耐药性大肠杆菌的丰度高于进水和二级处理出水。在二级沉淀池，AMX 耐药性大肠杆菌在回流污泥中得到富集。较高的温度也可能导致污泥中 AMX 耐药性大肠杆菌的增加。二级处理出水中大肠杆菌的抗生素耐药谱比进水更依赖于活性污泥。这些结果表明，WWTP 中的活性污泥可能是 ARB 的储存库，并且 WWTP 中 ARB 的行为因抗生素种类而异。
